Directive radio system



Aug. 15, 1939. E. BRUCE 2,169,553

DIRECTIVE RADIO SYSTEM Filed Sept. 11, 1936 s Sheets-Sheet 1 F/G. IA

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* OVAL DkUM REFLECTOR lNl ENTOR \j E. BRUCE J BY f K AT TORNEY E. BRUCE 2,169,553

DIRECTIVE RADIO SYSTEM Filed Sept. 11, 1936 5 Sheets-Sheet '2 FIG. 4

6 RECEIVER Q 7 r 5 *Ikifll/TTER fl'mundtter I 0r Receiver km 3 FIG. 6 3 INVEN TOR IKLTRANS'MITITER' RECEIVER I By E- BR E ATTORNEY Aug. 15, 1939. E. BRUCE ,169, 53

DIRECTIVE RADIO SYSTEM Filed Sept. 11, 1936 3 She ts-Sheet 3 Plaza-4" FIG.8B 98 FIG. lbA HQ ,0; 11% 13- lNl/ENTOR E. BRUCE ATTORNEY PatentedAug. 15. 1939 v 2,169,553

UNITED STATES PATENT O'FFlCE DIRECTIVE RADIO SYSTEM Edmond Bruce, Red Bank, N. 1., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application September 11,1936, Serial No. 160,287

17 Claims. (01. es -:11)

This invention relates to radio f transmitting diffraction zone plate or diffractor may be diand receiving systems and especially to ultraelectric or conductive. If dielectric, the focal short wave reflecting and diffracting apparatus. length is the same as that of the reflecting end As is well known waves having a length less plate of the container and, if metallic or conthan ten meters and commonly referred to as ductive, the focal length is preferably equal to ultra-short waves are quasi-optical in nature and or greater than a half wave-length. The anvarious systems comprising plane, parabolic and tenna is preferably placed a quarter wave-length spherical mirrors, gratings and zone plates, as from the reflector and coincident with the comfor example the systems disclosed in Patent mon line focus of the diifractor and the end 2,043,347, to A. G. Clavier and R. H. Darbord, plate of the container or reflector. l0 granted June 9, 1936, have been combined with The invention will be more readily understood radiating or absorbing non-directive antenna from the following detailed specification taken structures for the purpose of unidirectively transin conjunction with the drawings on which like mitting and receiving such waves. The mirrors. reference characters denote elements of similar 18 gratings and zone plates ordinarily employed function and on which: 5 each possess a point focus at which the antenna Figs. lA and l B are, respectively, crossis usually positioned. In practical systems, howsectional and front view of one embodiment of ever, linear antennas are employed. These anthe invention comprising an orbicular drum re? tennas do not possess a non-directional characflector; and Fig. 2 illustrates a perspective view teristic inall planes of propagationand absorb of the embodiment of Figs. 1--A and lB; 20

or emit energies at points other than the'point 3 illustrates another embodiment comfocus of the quasi-optical apparatus. Moreover, prising a cylindrical drum reflector; I

in the systems heretofore proposed, waves hav- Figs. 4 and 5 illustrate combined transmitting ing appreciable intensity and diverse propagaand receiving systems; tion directions other than the desired direction Fig. 6 illustrates a one-way communication 25 are ordinarily emitted or absorbed; and, as a system utilizing the invention;

result, the directive characteristic of the com- Fig. '7 illustrates the directive characteristics plete system includes, in addition to the major of various embodiments of the invention; and lobe, several minor lobes of large dimensions. Figs. 8-A, 8B, 9A, 9B, l0'A and 10-3 It is an object of this invention to achieve are diagrams useful for explaining the inv'en- 30 maximum unidirectivity in an ultra-short wave tion. communication system. Referring to Figs. 1-'A and l B, reference It is another object of this invention to connumeral i designates the 'cylindraceous side or form the finite focus of quasi-optical radio apwall, and reference numeralZ the end or bottom paratus to the finite dimensions of the antenna plane reflecting plate, of a drum container 3. A 35 associated therewith. doublet or linear antenna 4 a half wave-length It is still another object of this invention to long is positioned within the drum '3 and cenreduce or eliminate substantially the minor or tered on the longitudinal axis XX in a transsecondary lobes ordinarily unavoidably present verse plane Y-Y of the drum. The doublet is 40 in the directive characteristic or diagram of an connected to a translation device 5, which may 40 ultra-short wave radiating or absorbing system. be a transmitter or receiver and which is mount- According to one embodiment of this invened on the passive side of reflector plate '2, by tion, the above and other objects 'are accome means of line conductor 8. Each conductor 6. plished by positioning a linear doublet antenna is preferably enclosed in a coaxial shield 1. The

5 in a drum or cylindraceous container having an translation device 5 is for convenience enclosed open end and a closed end, and by positioning within'a compartment 8. formed by the extension a properly designed orbicular diffraction .zone of the drum 3 and a back cover member. -9. plate in the plane of the container opening. Members i, 2 and 9 are constructed of wood The differences between the maximum and minor other suitable material.

imum diameters of the zone plate, and between Reference numeral l0 designates a triple-zone 50 the maximum and minimum transverse dimenplate which is metallic or conductive and is p0 sions of the container, are each equal to the sitioned in the plane of the opening of drum .3. linear dimension of the doublet. The closed con- The diifractor I0 is constructed or dimensioned tainer end functions as a true reflector and the so as to block or prevent the propagation of encontainer side or wall functions as ashield. The ergy in the second zone, or zone B, and so i fas to permit energy propagation in the adjacent I extent and configuration with diifractor zone B,

may for economy be left exposed Or'unIined with copper. As will be explained more fully the drum is preferably arranged for rotation in a horizontal plane and in a vertical plane and may be accurately aligned with a desired direction i3 by means of a gun sight It. Reference numerals i5 designate struts for rigidly associating device 5 and diffractor ill with member 2'.

Considering the drum dimensionsin the plane of the drum opening, as illustrated by Fig. 1-3, the inside maximum diameter E exceeds the inside minimum diameter F by an amount equal to the length L of the linear antenna or doublet 4. Ordinarily the doublet is a half wave-length long. Similarly, considering the diffractor l0, both the inside maximum diameter G and the outside maximum diameter H exceed, respectively, the inside minimum diameter J and the outside minimum diameter K by an amount equal to the length L. The geometrical construction of the zone plate l0 and the reflector 2 are such that the reflector 2 and zone plate l0 each possess a line focus having a length corresponding to that of the doublet. Moreover, the reflector 2 and zone plate iii are spaced and positioned so as to have a common focus and the doublet 4 is positioned so as to coincide with this common line focus. The focal length M of the reflector is a quarter wave-length while the focal length D of the metallic zone plate Ill is at least one half wave-length. While the theory is not fully understood, it is believed that eddy or edge currents in the metallic zone plate in displace the diffractor focus and render. the focal length D of the difiractor unequal to the focal length M of the reflector. The zones of difiractor l0 and reflector 2, however, remain complementary. ,Diifractor plate ill may be composed of dielectric material and when so'formed its focal length D equals that of the reflector.

It will be observed that all points on the inner circumference of the plate iii are at the same distance, D plus a half wave-length, from the doublet 4. Similarly the distances between all points on the outer circumference and the doublet are the same and equal'to the focal distance D plus a wave-length. The radial width .of zone plate ill depends on the focal distance D and may be easily computed. In an experimental model, the dimensions given on Fig. 1-A, such as R=1,947\, were found satisfactory. The dimensions of the drum and diifractor may of course be,

different from those indicated in Fig. 1-A.

Assuming the system of Figs. 1-A and 1-3 is employed for receiving energy, the incoming wave propagated in a direction l3 coincident with axis XX and having a wave front perpendicular to said axis, intercepts the zone wave ID. The

energies passing through zones A and C are focussed upon the doublet and arrive in phase at the doublet inasmuch as these zones are, in effect, located at distances from the doublet diflering by a wave-length; The energy included in zone B is in phase opposition to the energy pass ng through zones A and C and is prevented from reaching doublet 4 by the plate Ill. Since each point on the path of propagation is itself a source of non-directional radiation, portions of the enerlobes of the directive characteristic of the systemare greatly reduced. The orbicular configuration of the diffractor l0 and the orbicular drum crosssection eliminate, or at least further decrease, the minor lobes. Obviously, in so far as the shielding function of drum 3 is concerned, the

configuration in a cross-sectional or transverse plane of drum 3 may be other than orbicular as for example circular or polygonal.

Referring to Fig. 2, the structure for steering or directively adjusting the embodiment illustrated by Figs. 1A and 1-3 is shown. The drum 3 is supported on the vertical axle i6 and the horizontal axle I! which in turn are supported by the wooden supporting structure i8. The drum may be rotated about axle I6 by means of handle I9 and rotated about axle H by means of wheel 20 so that axis X-X of the drum may be aligned with any direction. A scale 2| and pointer 22 are provided for indicating the elevation angle of adjustment, and a scale 22 and pointer 23 are included for indicating the azimuth angle. Obviously other means for accurately pointing or directing the drum 3 may be employed.

Referring to Fig. 3, reference numeral 24 denotes the drum reflector which is the same as reflector 3 except that it has a circular cross-section. This reflector is suitable for use with a point antenna structure, such as a doublet antenna having an overall length of the order of one hundredth of a wave-length, or an antenna structure arranged to emit or receive circularly polarized waves. Numeral 25 denotes a zone plate which is the same as plate l0 except it is circular lized. Reference numeral 2'! denotes a partition which divides the compartment 8, in two parts,

one of which contains a transmitter and the other of which contains a receiver. As illustrated, the transmitter 5 is associated with one doublet I and associated drum 3 and the receiver 5 is associated with thejother'doublet I and drum 3. The duplex or combined system is mounted or supported by structure l3, and as in the system of Fig. 2, may

be rotated as indicated by arrows 28 abouta horizontal axle i1 and about a vertical axle it so that the direction of transmission or reception may be successively aligned with the same desired path of radiant action.

Fig. 5 illustrates a system in which the same \antenna and drum 3 are used, successively, for

transmission and reception. The doublet I may be connected to either the transmitter 5 or re- Fig. 6 illustrates a one-way system comprising a transmitting system and a receiving system either or both of which may be movable or stationary. Each system comprises the embodiment illustrated by Figs. 1-A, 1--B and 2 and need not be explained in detail here. The systems are aligned for directive communication.

Referring to Fig. 7, the solid or full line curve 30 designates the azimuth or horizontal directive characteristic of the system illustrated by Figs. 1-A and 1-B and employing vertically polarized waves, and the dot-dot curve 3| illustrates the vertical or elevation characteristic. Curve 32, shown in dash-dash line, illustrates the azimuth directive characteristic of a cylindrical system of the same-construction as that illustrated by Fig. 3. The dot-dash curve 33 illustrates the directive characteristic in azimuth of a circular system in which the diffractor plate is omitted. It will be noted that the directive characteristic or curve 32 for the circular arrangement includes the large minor lobes 34, and the corresponding directive diagram 30 for the orbicular system does not include large minor lobes. Also, it will be noted that the omission of the diflractor plate I produces the broad directive characteristic 33 and the exceedingly large minor lobes 35.

The theory explaining the function of the orbicular shield in eliminating the minor lobes will be explained in connection with Figs. 8-A, 8B, 9A, 9-B, 10A and 10B and is analogous to that underlying the binominal antenna array disclosed in Patent 1,643,323 granted September 27, 1927, to John S. Stone. Referring to Fig. 8-A and assuming the drum diameter is one wavelength, the effective area at the opening of the drum as modified may be considered as being divided into two equal parts, A, each a half wavelength wide. The two areas A may be likened to two equally energized linear antennas. Curve 36 of Fig. 8B represents the figure of eight diagram produced by such a system. Referring to Fig. 9A, if the drum is one'and a half wavelengths in diameter, it may be divided into three areas each a half wave-length wide, the two end areas being equal and the central area 2A being twice as great as each of the end areas A. These areas may also be likened to linear antennas, the energization of the central linear antenna being twice that of either of the end linear antennas,. as in a binomial array of three elements, whereby a fairly sharp directive diagram 37 as illustrated by Fig. 9B is obtained. Referring toFig. 10A and assuming the drum diameter to be two wave-lengths, each of the central areas 3A is three times either end area IA. The'system of Fig. 10A produces the exceedingly sharp diagram 38 illustrated by Fig. 10B.

'Itwill be noted that the directive diagrams of Figs. 8-B, 9B and 10B do not contain minor lobes. The relation of the effective areas is not materially changed when diifractor plates are utilized. It follows that the wall I of the drum 3, in a sense conforms or proportions the effective reception or radiation area of the system to the binomial theorem, whereby minor lobes are eliminated 'and'an exceedingly sharp major lobe is secured.

Although the invention has been described in connection with certain embodiments thereof, it is to be understood that it is not to be limited to such embodiments and that other apparatus and arrangements may be utilized without exceeding the scope of the invention.

What is claimed is:

1. In a radio system, a linear antenna, a flat zone reflector having a line focus equal in length to said antenna, said antenna being superimposed on said focus.

2. Ina radio system, a linear antenna, a zone diffractor having a line focus equal in length approximately to said antenna, said antenna being superimposed on said focus.

3. In a radio system, an antenna, a reflector, a diifractor, said antenna being included between said reflector and diffractor.

4. In a radio system, a linear antenna, an orbicular reflecting zone plate, an orbicular diffracting zone plate, said plates being positioned in parallel planes and having a common line focus, said antenna being included between said plates and positioned coincident with said focus.

5. In a radio system, a metallic container having an opening at one end only and being otherwise closed a reflection grating and means for aligning the periphery of the opening so that the opening is substantially included in a plane parallel to'said grating, and an antenna positioned in said container and at the focus of said grating. I

6. In a radio system, a linear antenna, a cylindraceous metallic container having an open and a closed end, the difierence between the maximum and minimum transverse dimensions of said container being approximately equal to the length of said antenna and the closed end member of said container constituting a zone plate, said antenna being positioned in said container and at the focus of said plate.

'7. In a radio system, a linear antenna, a reflecting plate, a conductive diifracting plate, said antenna being positioned a quarter wave-length from the reflecting plate and at least a half wavelength from said diffracting plate and at the common focus of said plates.

8. In combination, a linear antenna, and an orbicular diffraction zone plate, the difference be' tween the maximum and the minimum diameters of any zone being equal to the length of said antenna, said antenna being positioned coincident with the line focus of said plates.

9. In combination, a linear antenna, an orbicular diflraction zone plate, a complementary reflection zone plate, the difference between. the maximum and minimum diameters of each zone of each plate being equal to the length of said antenna, said antenna being positioned coincident with the common line focus of said plates.

10. In combination, a linear antenna, an orbicular diffraction zone plate, a complementary reflection zone plate, the difference between the maximum and minimum diametersof each zone of each plate being equal to the length of said antenna, said antenna being positioned a quarter wave-length from said reflecting plate and at the line focus of said diffraction plate.

11. In combination, a linear antenna, an orbicular dielectric diffractor, a complementary metallic reflector, said diifractor and reflector having equal finite focal lengths and being positioned to have a common line focus, and said antenna being positioned coincident with said focus.

' 12. In a radio system, a linear antenna, a plane zone reflecting plate, a plane zone diffraction plate, the differences between the maximum and minimum diameters for each zone of each of said plates being equal to the length of the linear antenna whereby said plates'each possess a line focus, said plates being, positioned to have a common focus and said antenna. being superimposed on said focus, and a shield extending between said plates for preventing-radiant action in undesired directions.

13. In a radio system, a drum comprising a tubular wall structure open at one end and having an end member serving as a closure for the other end, the wall of said drum constituting a shield and the closed end member constituting a zone reflector, an antenna positioned at the focus of said reflector, and means for adjusting the direction of radiant action of said system.

14. In a radio system, a drum comprisinga tubular wall structure open at one end and having an end member serving as a closure for the other end, the wall of said drum constituting a. shield and the closed end member constituting a zone reflector, a diflractor positioned parallel to said reflector, an antenna included in said drum and at the focus of said reflector and difl'ractor, and means for aligning the longitudinal axis 01' said drum with any desired direction.

15. In a radio system, an antenna, a circular drum open at one end and having an end member serving as a closure for the'other end, the wall 01' said drum constituting a shield and the closed end member constituting a zone reflector, said antenna being included in said drum and positioned in a plane parallel to the plan of the reflector.

16. In a radio system, a cylindrical walled container open at one end and having an end closure member flxed thereto at the opposite end to constitute a drum, the wall of said drum constituting a shield and the closed end member constituting a zone reflector, a pair of perpendicularly related linear antennas, a phase shifter, a translation device, said antennas being positioned within said drum, one of said antennas being directiy connected to the translation device and the other being connected thereto through the phase shifter.

17. In a radio system, a tubular walled container open at one end and having an end member fixed thereto and forming a closure for the other end to constitute a drum, the wall of said drum constituting a shield and the closed end member constituting a zone reflector, an antenna positioned therein, a radio terminal apparatus, and means for connecting the terminal apparatus to said antenna. 7

EDMOND BRUCE. 

